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        var myname;
        myname ='giao?';
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    <script>
        // var age = 'giaowodiu'
        // console.log(age);
        /* var myname = 'lsf' , age = 20, sex = 'man';
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       /*  var age  ;
        console.log(age); 未赋值 */
        // console.log(age); 未声明，且未赋值

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